1. Field of the Invention
The invention relates to a vehicle, and more particularly, to an art of determining whether or not there is a malfunction in an engine that is mounted on the vehicle.
2. Description of Related Art
In Japanese Patent Application Publication No. 2012-36767 (JP-2012-36767 A), there is disclosed an art of performing idle-up control in determining, on the basis of a combustion state of an engine during a period in which the engine rotates a predetermined reference number of times, whether or not there is a malfunction in the engine to thereby make a time required for the determination on the malfunction shorter than during normal idling.
In recent years, vehicles (so-called plug-in hybrid vehicles) that run by at least one of a motive power of a motor and a motive power of an engine and allow a battery, which stores an electric power to be supplied to the motor, to be charged with an electric power from a vehicular external power supply have been put into practical use.
In each of the plug-in hybrid vehicles, a mode (a CD mode) in which the engine is not allowed to be driven to hold a state of charge (an SOC) of the battery within a predetermined range is selected until the SOC of the battery falls to a lower limit. Thus, the frequency with which the engine operates is relatively low until the SOC of the battery falls to the lower limit. On the other hand, a mode (a CS mode) in which the engine is allowed to be driven to hold the SOC of the battery within the predetermined range is selected after the SOC of the battery has fallen to the lower limit. Thus, the frequency with which the engine operates is relatively high after the SOC of the battery has fallen to the lower limit.
In such a plug-in hybrid vehicle, for example, in the case where the vehicle runs a short distance from an almost fully charged state of the battery, the CD mode may be selected in an almost entire period during one trip (a period from activation of a vehicle system to subsequent stop thereof). In this case, the frequency with which the engine operates is low. Thus, the number of times of rotation of the engine during one trip may not reach a reference number of times, so that a malfunction in the engine may be detected with delay. In this case, when idle-up is carried as described in Japanese Patent Application Publication No. 2012-36767 (JP-2012-36767 A), a deterioration in fuel economy or emission properties may be temporarily caused.